If you are working from a PDF from Outerzone then if the plan is printed using the "full size" option when using Adobe Acrobat Reader then it will print very close to the proper size. For the prints I've done any errors were either minor or were some distortion in only one axis due to the printer not pulling the paper through the rollers at the proper speed or something like that.

If you want to resize a design then again using Adobe Acrobat Reader there is an option to print to some percentage of the original size. You can go from a small 10% size up to over 200%. It probably permits bigger but I've never tried it. Fair warning though.... If you try to scale a design by more than about 20% smaller or bigger you start to run into the possibility that you should alter the structure. Things like adjusting the number of wing ribs so the covering is suitably supported if making the model bigger is one of those. And if you shift by more than 20% either way then wood sizes start to require changing to the next thickness up or down. So try to pick a design that starts out close to what you want for size.